The present invention relates to a cutting method for an inner circumferential face and an outer circumferential face of a work using a cutting tool of a main shaft which turns around a predetermined position serving as a center and for which a turning radius is adjustable, the cutting being performed by increasing a cutting velocity of the cutting tool.
The “turning of the main shaft” is not limited to rotation of the main shaft along a central axis thereof but refers to rotations including revolution of the main shaft around the predetermined position serving as a center.
What is called an orbit machining that a main shaft turns around a predetermined center has been adopted as a method for forming an inner circumferential face and an outer circumferential face of a work into curved faces variously shaped like cylinders, tapered shapes, flanges, or the like, as disclosed in Patent Literature 1. This machining method is technically advantageous in that machining can be achieved at whatever position a table supporting the work is located.
However, in the orbit machining method according to the related art, the work is not rotated, and cutting is performed only by turning the main shaft. Thus, the cutting velocity is limited.
For cutting of the work, Patent Literature 2 proposes a cutting method involving movement of a table supporting a tool in addition to rotation of the main shaft.
However, in the method in prior arts, the table moves linearly by using ball screw, and no increase of the turning angular velocity of the main shaft is configured (see FIG. 2, and differential equation (1), and (2) in section).
Furthermore, the rotation of the main shaft and the movement of the table need to be controlled based on complicated expressions (for example, expressions (5)-(99) shown in sections.
Patent Literature 3 proposes a configuration in which the rotation of the main shaft be reinforced by circular arc motion of the work. However, the configuration needs to be controlled based on complicated operations in which the number of rotations of the main shaft is synchronized with the relative circular-arc complemental motion of the work in a predetermined ratio.
Thus, for the cutting of the inner circumferential face or the outer circumferential face of the work, no cutting method has been proposed to increase the cutting velocity of the cutting tool and to provide a simple control for increase.